product.id from orderlines.xlsx are the same as bike.id from bikes.xlsx
Therefore they are combined (both dataset share product.id)
Combining customer.id from orderlines.xlsx and bikeshop.id from bikeshops.xlsx
Because the bikeshops (middle man) are buying and selling to customers, therefore they are the customer of the supplier (Seller)
dplyr::left_join(orderlines_tbl, bikes_tbl, by =c("product.id"="bike.id"))
bike_orderlines_joined_tbl = orderlines_tbl %>% dplyr::left_join(bikes_tbl, by =c("product.id"="bike.id")) %>% dplyr::left_join(bikeshops_tbl, by =c("customer.id"="bikeshop.id"))head(bike_orderlines_joined_tbl, n =5)